Defining an environmental indicator for soil quality
Soil is just as important a natural resource as water, air and the biosphere, but often receives the least attention. Soil quality is diminished by a number of anthropogenic activities in towns and cities. Yet, prior to the URBSOIL project, no common methodology existed to assist municipal authorities in monitoring trends in soil quality. The central element of the concept developed at the University of Torino is the definition of an indicator entitled Environmental Quality (EQ), the value of which indicates the health of the soil at a particular location. The EQ is determined by measuring a number of quantitative soil and degradation parameters as listed in the Minimum Data Set (MDS). The MDS also includes some qualitative information about the sampling location. A simple rating scale allows for the generation of a numeric score (EQ) for each site. Depending on the value of the EQ, the site is categorised as bad (i.e. requiring remediation), average or high (i.e. little evidence of human intervention) environmental quality. In order to facilitate the implementation of the framework, the Italian scientists recommend that each city set aside several Permanent Monitoring Areas (PMAs) within their urban boundaries. The number of PMAs required depends on the size of the city. Each PMA should cover approximately 50000 square meters and ideally should be co-located with other monitoring equipment (e.g. air quality monitoring stations). As opposed to spot sampling, PMAs offer advantages in temporal and spatial resolution as well as multi-component analysis. Care should be taken to avoid locating PMAs close to significant point sources of pollution. The University has provided specific guidance concerning what soil parameters should be measured and how often they should be measured at the PMAs. The framework is simple and also flexible, allowing each city to define its own EQ class demarcations. Data requirements are not overwhelming, nor are they driven by rigid constraints. In addition to the information it provides by itself, the EQ indicator can help form part of a larger Decision Support Tool. It is hoped these developments will contribute to more sustainable management of soil resources.
